Hand-operated pipette

ABSTRACT

A hand-operated portable pipette is disclosed which includes a housing, a flexible tube mounted therein along a path. The tube has a first end thereof mounted for movement with respect to the housing. A trigger is also mounted on the housing to operate a roller for occluding the tube along a portion of the path in response to movement of the trigger. The trigger is biased to a rest position. A multifaced cam is mounted as an adjustable stop for determining the nominal maximum travel of the trigger. A spring loaded over-travel stop is mounted in the trigger to interact with the multifaced cam so that a first force applied to the trigger will cause the spring loaded over-travel stop to rest against the face of the multifaced cam bringing the trigger to rest at a first position. If additional force is applied to the trigger, the spring loaded over-travel stop depresses into the trigger extending the movement of the trigger to allow the tube to be occuluded further along the path. A disposable tip is inserted in a movable end of the tube to allow changing thereof. A second trigger, arm, and sleeve are used to eject the disposable tip after usage.

United States Patent [191 Berman et al.

[ Jan. 22, 1974 HAND-OPERATED PIPETTE v [75] Inventors: Richard M. Berman, Dresher, Pa.;

Bernard Schwartz, Springfield, NJ.

[73] Assignee: Alphamedics Mtg. Corp., Levittown,

[22] Filed: Sept. 12, 1972 [21] Appl. No.: 288,266

[52] US. Cl. 73/425.4 P, 73/4256, 222/79, 417/476 [51] Int. Cl...... G0ln 1/10, A63h 3/18, F04b 43/08 [58] Field of Search 417/474, 476; 222/214, 210, 222/79; 73/425.4 P, 425.6

Raczak 73/4256 Primary Examiner-William L. Freeh Assistant Examiner-Richard E. Gluck [57] v ABSTRACT A hand-operated portable pipette is disclosed which includes a housing, a flexible tube mounted therein along a path. The tube has a first end thereof mounted for movement with respect to the housing. A trigger is also mounted on the housing to operate a roller for occluding the tube along a portion of the path in response to movement of the trigger. The trigger is biased to a rest position. A multifaced cam is mounted as an adjustable stop for determining the nominal maximum travel of the trigger. A spring loaded overtravel stop is mounted in the trigger to interact with the multifaced cam so that a first force applied to the trigger will cause the spring loaded over-travel stop to rest against the face of the multifaced cam bringing the trigger to rest at a first position. If additional force is applied to the trigger, the spring loaded over-travel stop depresses into the trigger extending the movement of the trigger to allow the tube to be occuluded further along the path. A disposable tip is inserted in a movable end of the tube to allow changing thereof. A second trigger, arm, and sleeve are used to eject the disposable tip after usage.

10 Claims, 2 Drawing Figures HAND-OPERATED PIPETTE FIELD OF THE INVENTION This invention relates to pipettes and particularly to portable hand-operated pipettes.

BACKGROUND OF THE INVENTION Traditionally when quantative analysis of chemical solutions had been performed, the measurement of precise small volumes of the solutions was done by drawing the fluid into a glass tube by mouth created suction and holding a finger over the end of the tube to hold the measured liquid therein. The measured quantity of the liquid is released into a receptacle for processing by letting go of the opened end of the tube.

The process exposes the chemicals sampled to the possibility of bacterial contamination because the source of suction is the human mouth. A further drawback associated with this process is the possibility of injuring the operator if by some chance the liquid being pipetted is accidentally drawn into his mouth.

Attempts have been made to employ piston operated suction devices such as hypodermic needles to accurately transfer chemicals. It has been found that wear at the piston or the sealing ring in such devices renders them unsuitable for accurate transferring which is necessary in many chemical analyses.

In each of the above approaches to accurately transfer small quantities of chemical substances, glass tubes are used to contain the samples so that they can easily be cleaned to prevent cross-contamination from sample to sample or from chemical to chemical. For this reason, peristaltic pumps which are used in other areas for accurately transferring liquid have not been thought suitable since the basic principal of the peristaltic pump requires that the tube in which the liquid is drawn be compressible;

Therefore, it is an object of this invention is to provide a new and useful device for accurately transferring small quantities of chemical fluids.

It is a further object of this invention to provide a device for accurately transferring small quantities of chemical substances which are free from biological contamination.

It is another object of this invention to provide a device for the accurate transfer of small quantities of chemical chemical substances which does not require the use of a piston or ring which is susceptible to wear. It is still another object of this invention to provide .a device which is not subject to operator error or BRIEF DESCRIPTION OF THE INVENTION With these and other objects in view the present invention contemplates a hand-operated pipette in which a flexible tube is mounted in ahousing along a fixed path. A trigger is mounted on the housing for movement between first and second positions. A roller is mounted in the housing for creating an occlusion in the flexible tube on the path. The roller is arranged to create the occlusion at a first point on the flexible tube when the trigger is in the first position and is responsive to the trigger being moved from the first to the second position for moving the occlusion along the flexible tube from a first point to a second point displaced a predetermined distance along the path from the first point. In this way a hand-operated peristaltic pump is provided for smapling predetermined accurately controlled volumes of liquid.

In the preferred embodiment of this invention the trigger is normally biased to the first position and is responsive to a first force level applied thereto to move from the second position to a third position. In this way an over-travel movement may be employed overcoming surface tension in a last drop which may be ejected from the tube.

A further aspect of the preferred embodiment of this invention resides in the fact'that a disposable tip is employed having a passage therethrough capable of holding a larger volume than the volume drawn by the pump upon operation of the trigger. Therefore, when the pump is operated the disposable tip holds all of the liquid and no liquid enters the flexible tube. Therefore no contamination thereof is possible. The disposable tip is particularly useful when chemical or biological fluids (such as blood) are to be transferred. The tips may be ejected after each operation to prevent contamination from sample to sample, or when the nature of the fluid being sampled is changed to prevent crosscontamination of or reactions between samples having different chemical compositions.

DESCRIPTION OF THE DRAWING FIG. 1 is a cutaway view of a hand-operated pipette constructed in accordance with the teaching of this invention; and

FIG. 2 is a section view of tip portions of the pipette of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIGS. 1 and 2, we see a handoperated pipette 10 having a housing 11 in which the various elements of the pipette are mounted. The pump includes a flexible tube 12 mounted in the housing and having a first portion thereof 13 which lies along the path between a stator 14 and a roller 16. The tube 12 extends over the rear portion of housing 11 and terminates in a rotatable mounting 18. A disposable tip 20 is mounted in the end of the housing 11 by fitting over an O ring seal 28. The tip ejector consists of a movable sleeve l7 which slides on housing 11, and an arm 29 and pivot 30.

The roller 16 is mounted on an arm 19 of a trigger assembly 21. The trigger assembly 21 is in turn pivotally mounted on a pin 22 affixed to the housing 11. A spring 23 biases the trigger assembly 21 to a first position defined by a stop post 24. A spring loaded stop member 26 is mounted in the trigger assembly 21 to cooperate with a multifaced positionally adjustable cam 27 to determine the various travels of the roller 16 from the rest position defined by the spring 23 and the stop post 24.

The hand-operated peristaltic pump 10 may be employed for taking small samples of a liquid and transferring them to containers for chemical reaction or analysis. To do this an operator would grasp the pump I0 using the housing 11 as a handle and placing a finger or fingers on the trigger 21. The rotatable mounting 18 would be pivoted to put the disposable tip 20 in an appropriate position for immersion in a body of fluid while the housing 11 is oriented to a comfortable operating position. The multifaced cam 27 is adjusted to provide an appropriate face opposite the stop member 26 which results in the pump sampling a desired quantity of fluid. The trigger 21 is then depressed until the stop member 26 rests firmly against the fact of the cam 27. As the trigger 21 is depressed the roller 16 occludes the tube 12 along a predetermined distance along the path exhausting air as it moves.

The trigger 21 is then released. The spring 23 forces the trigger 21 back to its rest position defined by the stop post 24. This moves the roller 16 back along the tube 12 drawing a preset volume of fluid into the pump 10. In this embodiment the volume of fluid which can be contained in the disposable tip 20 is greater than the maximum capability of the pump in that all of the fluids sampled remain in the tip 20.

The pump is then moved to a receptacle into which the sample of fluid is to be dispensed. The trigger 21 is again depressed to dispense the fluid in the tip into the receptacle. 1n the preferred embodiment of this invention the stop member 26 is spring loaded by a spring 35 so that further force being applied to the trigger 21 will force the stop member into the trigger allowing the roller 16 to move further along the tube 13 than it had when the sample was taken. This small additional movement of the roller 16 allowed by spring loading the stop member 26 allows additional force to be applied to the sample in the tip 20 to overcome surface tension in the last drop to insure that an accurately measured sample is dispensed.

The used tip is ejected by pressing trigger 29 which forces sleeve 17 to expell tip 20 from tube 11. Spring 31 returns trigger 29 to its original position.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, only by the appended claims.

What is claimed is:

1. A hand-operated pipette including:

a housing;

a flexible tube mounted in said housing to define a path;

a trigger mounted on said housing for movement between the first and second position, said second position being defined by a spring loaded stop member carried by said trigger which inhibits movement of said trigger beyond said second position in response to a force below a predetermined level and allows movement of said trigger beyond said second position to a third position in response to a force applied thereto which is greater than said predetermined level; and

depressing means mounted in said housing for creating an occlusion in said flexible tube on said path; said depressing means being arranged to create said occlusion at a first point; said depressing means being responsive to said trigger moving from said first to said second position for moving the occlusion along said path from said first point to a second point; said second point being displaced a predetermined distance along said path from said first point; said depressing means being responsive to said trigger moving to said third position for moving said collusion to a third point on said path which is a greater distance from said first point than said second point is.

2. The hand-operated pipette as defined in claim 1 also including:

a stator mounted in said housing; and said flexible tube has atab formed thereon; said tab mating with said stator to mount said flexible tube in said housing and to define said path.

3. The hand-operated pipette as defined in claim 1 also including:

a disposable tip;

means for securing said disposable tip to said flexible tube; and

tip ejection means mounted on said housing.

4. The hand-operated pipette as defined in claim 1 also including;

a stator mounted in said housing; and said flexible tube has a tab formed thereon; said tab mating with said stator to mount said flexible tube in said housing and to define said path.

5. A hand-operated pipette including:

a housing;

a flexible tube mounted in said housing to define a path;

a trigger mounted on said housing for movement between a first and second position;

depressing means mounted in said housing for creating an occlusion in said flexible tube on said path; said depressing means being arranged to create said occlusion at a first point; said depressing means being responsive to said trigger moving from said first to said second position for moving the occlusion along said flexible tube from said first point to a second point; said second point being displaced a predetermined distance along said path from said first point; and

second position defining means for defining said second position; said second position defining means including adjustable means for allowing the maximum travel of said trigger to be adjusted.

6. The hand-operated pipette as defined in claim 5 in which said trigger is biased to normally rest in said first position.

7. The hand-operated pipette as defined in claim 6 in which said adjustable means includes:

a multifaced cam mounted for movement in said housing to provide an adjustable stop for said trigger.

8 The hand-operated pipette as defined in claim 7 in which said depressing means includes:

a roller mounted for movement along said path.

9. The hand-operated pipette as defined in claim 5 also including:

a disposable tipe;

means for securing said disposable tip to said first end of said tube; and

a tip ejector mounted on said housing.

10. The pipette as defined in claim 9 in which said trigger is brought to said first position and is responsive to a first force level applied thereto to move from said first position to said second position and to a second force level applied thereto to move from said second position to a third position. 

1. A hand-operated pipette including: a housing; a flexible tube mounted in said housing to define a path; a trigger mounted on said housing for movement between the first and second position, said second position being defined by a spring loaded stop member carried by said trigger which inhibits movement of said trigger beyond said second position in response to a force below a predetermined level and allows movement of said trigger beyond said second position to a third position in response to a force applied thereto which is greater than said predetermined level; and depressing means mounted in said housing for creating an occlusion in said flexible tube on said path; said depressing means being arranged to create said occlusion at a first point; said depressing means being responsive to said trigger moving from said first to said second position for moving the occlusion along said path from said first point to a second point; said second point being displaced a predetermined distance along said path from said first point; said depressing means being responsive to said trigger moving to said third position for moving said collusion to a third point on said path which is a greater distance from said first point than said second point is.
 2. The hand-operated pipette as defined in claim 1 also including: a stator mounted in said housing; and said flexible tube has a tab formed thereon; said tab mating with said stator to mount said flexible tube in said housing and to define said path.
 3. The hand-operated pipette as defined in claim 1 also including: a disposable tip; means for securing said disposable tip to said flexible tube; and tip ejection means mounted on said housing.
 4. The hand-operated pipette as defined in claim 1 also including; a stator mounted in said housing; and said flexible tube has a tab formed thereon; said tab mating with said stator to mount said flexible tube in said housing and to define said path.
 5. A hand-operated pipette including: a housing; a flexible tube mounted in said housing to define a path; a trigger mounted on said housing for movement between a first and second position; depressing means mounted in said housing for creating an occlusion in said flexible tube on said path; said depressing means being arranged to create said occlusion at a first point; said depressing means being responsive to said trigger moving from said first to said second position for moving the occlusion along said flexible tube from said first point to a second point; said second point being displaced a predetermined distance along said path from said first point; and second position defining means for defining said second position; said second position defining means including adjustable means for allowing the maximum travel of said trigger to be adjusted.
 6. The hand-operated pipette as defined in claim 5 in which said trigger is biased to normally rest in said first position.
 7. The hand-operated pipette as defined in claim 6 in which said adjustable means includes: a multifaced cam mounted for movement in said housing to provide an adjustable stop for said trigger. 8 . The hand-operated pipette as defined in claim 7 in which said depressing means includes: a roller mounted for movement along said path.
 9. The hand-operated pipette as defined in claim 5 also including: a disposable tipe; means for securing said disposable tip to said first end of said tube; and a tip ejector mounted on said housing.
 10. The pipette as defined in claim 9 in which said trigger is brought to said first position and is responsive to a first force level applied thereto to move from said first position to said second position and to a second force level applied thereto to move from said second position to a third position. 